Inkjet imaging devices produce text and images on a substrate such as paper by ejecting minute quantities of ink from a reservoir onto the substrate in response electrical commands. The electrical commands activate small orifices or inkjets in a print head to eject the ink in the desired locations to form the desired images. Because the ink in an inkjet imaging device is used up eventually in the printing process, conventional inkjet imaging devices include the ink reservoir in a replaceable cartridge commonly referred to as an inkjet cartridge. The print head containing the orifices through which the ink is ejected is also commonly included in the replaceable inkjet cartridge. The remainder of the inkjet imaging device includes electrical control components and mechanical components for moving the inkjet cartridge with respect to the printing substrate (paper) and for moving the substrate with respect to the inkjet cartridge.
Photocopiers, printers, plotters, and facsimile machines are examples of devices that may utilize an inkjet printing or imaging process. As used in this disclosure “inkjet device” encompasses any type of device using an inkjet process. Also, for purposes of the following description, the portion of the inkjet device other than the inkjet cartridge will be referred to herein simply as an inkjet device whether or not the inkjet cartridge is installed. The portion of the inkjet device that carries the consumable ink for the inkjet imaging process will be referred to as an inkjet cartridge (also referred to throughout this disclosure simply as a “cartridge”) regardless of the particular design and regardless of the other components included on the device such as a print head and associated electrical lines and contacts.
FIG. 1 is a view in perspective of a typical prior art inkjet cartridge 100. Inkjet cartridge 100 includes a container 101 adapted to contain a supply of ink (the ink not being shown in the figure). The bulk of container 101 is generally rectangular in shape with a lower portion 102 projecting from the rest of the container. Print head assembly 104 is located on lower portion 102 of container and includes a large number of minute, electrically stimulated orifices or inkjets 105 through which ink from container 101 is ejected in the printing process. It will be appreciated that the orifices or inkjets are shown diagrammatically in FIG. 1 in an exaggerated scale, and that the orifices are in fact very small in order to produce the desired image resolution. The commands or electrical stimuli required to operate the orifices or inkjets 105 are applied to print head assembly 104 through electrical conductors 106 which terminate at contact pads 107 on a side of container 101. An inkjet printing device in which cartridge 100 is to be used will include a corresponding set of electrical contacts exposed so as to make contact with contact pads 107 on the cartridge. The electrical signals required for operating print head assembly 106 originate from a print control system (not shown) included in the inkjet imaging device. The illustrated prior art inkjet cartridge 100 also includes additional orifices facilitating fluid communication to ink container 101. The first additional orifice comprises an opening 109 commonly referred to as a vent opening or vent hole. The second additional orifice comprises an opening which is commonly referred to as a maze opening or maze hole located on the surface of cartridge 100 indicated by arrow 110. The maze hole is associated with a ball that functions as a check valve to prevent the flow of material out of container 101.
Due to space limitations and other physical restrictions in inkjet devices, inkjet cartridges typically have a relatively limited supply of the ink for use in the inkjet printing process. The working life of the print head assembly of an inkjet cartridge is, in fact, commonly much greater than the working life of the ink supply in the cartridge. Thus, although original equipment manufactures may prefer for inkjet device users to use totally new inkjet cartridges due to the relatively high profit margins associated with selling new inkjet cartridges, it is commonly possible to refurbish and reuse inkjet cartridges many times before they are no longer serviceable. The refurbishing equipment, however, must be easy to use and relatively inexpensive in order to maximize the price advantage of the refurbished inkjet cartridges over new inkjet cartridges.